Generally speaking mobile imaging barcode scanner with limited scanner module dimensions suffers from illumination related barcode scan difficulties. As the typical scanner illuminator has close proximity to the imaging lens, strong specular reflection can contaminate the image especially for highly reflective barcode. Direct product marking (DPM) type of barcode with metallic or laminated material are commonly adopted in the industry. For this kind of barcode application, mobile imaging barcode scanners show poor performance as compared with traditional imaging scanners. Dedicated DPM imaging scanner approaches, such as dome shape illuminator and ring shape dark field illuminator, cannot be directly applied to the mobile imaging barcode scanner due to the space requirement.
With the introduction of slim mobile data terminal types of barcode scanners there is a need to provide DPM barcode scanning solution for the front end mount imaging scanner module.